Chapter 26: Phylogeny and the Tree of LifePhylogeny: the evolutionary history of a species or group of related speciesSystematics: an analytical approach to understanding the diversity and relationships of organismsConcept 26.1: Phylogenies show evolutionary relationshipsTaxonomy: the ordered division of organisms into categories based on a set of characteristics used to assess similarities and differencesBinomial Nomenclature: The two part format of the scientific name of anorganism The binomial name consists ofo Genus and specieso These are always written in a differentfont (e.g., italics)o Genus is always capitalized; species isalways lowercaseo E.g., Homo sapiensHierarchical Classification: Linnaeus also introduced the system forgrouping species in increasingly broadcategories K eep Pipes Clean OF GaS – Kingdom,Phylum, Class, Order, Family, Genus, Species K indly Professors Cannot Often Fail Good Students i. Kingdom - Animaliaii. Phylum – Chordataiii. Class – Mammaliaiv. Order – Primatesv. Family – Hominidaevi. Genus – Homovii. Species – Homo sapiensLinking Classification & Phylogeny: Systematists depict evolutionary relationshipsin branching phylogenetic trees Each branch point (node) represents thedivergence of two species Deeper branch points represent greateramounts of divergence Lines represent lineagesInterpreting Phylogenetic Trees: INSERTPICTURE Interior nodes represent commonancestors Taxa at tips represent livingspecies/groups Rotating around any node leaves aphylogeny unchanged Which taxon on the tree below is most closelyrelated to taxon C?i. Aii. Biii. Div. B and D are equally closely related to Cv. All of the above are equally closely related to CWhich taxon on the tree below is most closely related to taxon A?i. Bii. Ciii. Div. All of the above are closely related to AWhich of the following represents the correct order of taxa, from the most inclusive to the least inclusive?i. Domain, Kingdom, Phylum, Class, Order, Family, Genusii. Species, genus, family, order, class, phylum, kingdomiii. Class, domain, family, genus, kingdom, order, phylumiv. Domain, phylum, order, family, class, genusConcept 26.2: Phylogenies are inferred from morphological and molecular dataMorphological & Molecular Homologies: Phylogenetic history can be inferred from similarities in homologous structures and genes when compared among organisms Generally, similar morphology and similar DNA sequences = closely related species But, beware of analogous structures or molecular sequences (a.k.a., homoplasies)o Similarity may be due to convergent evolution (analogy), not shared ancestry (homology)Concept 26.3: Shared characters are used to construct phylogenetic treesCladistics: Cladogram – a diagram depicting patterns of shared characteristics among species Clade within a cladogram – a group of species that includes an ancestral species and all ofits descendants Monophyletic Grouping: Made up of an ancestral species and all of its descendants Only monophyletic groups qualify as legitimate taxa in cladisticsParaphyletic Grouping: Consists of an ancestor and some, but not all, of that ancestor’sdescendants Polyphyletic Grouping: Grouping that lacks the common ancestor the species in the groupShared Ancestral & Shared Derived Characteristics: Shared ancestral characteristic: homologous structure that predates the branching of a particular clade from other members of that clade Shared derived characteristic: evolutionary novelty unique to a particular cladeWhich shared derived character allows us to infer that ((stink bugs + beetles) + lobsters is a clade?i. 1 pair antennaeii. Large clawsiii. Compound eyesiv. 6 legs Which of the following is not a shared ancestral trait of the ((stink bugs + beetles) + (lobsters)) clade?i. 6 legsii. 1 pair of antennaeiii. simple eyesiv. molt skeleton Is the similarity between the Australian mole and the NorthAmerican mole due to homology?1. Yes, they share a recent common ancestor2. No, they are similar due to random factors3. No, they are similar due to convergent evolution analogous Concept 26.4: An organism’s evolutionary history is documented in its genomeGene Duplications and Gene Families: Gene duplication: the production of multiple copies of a gene within the genome Important type of mutation in evolution because it increases the number of genes in the genome Orthologous & Paralogous Genes: Orthologous genes: genes foundin a single copy in the genomeo Diverge only oncespeciation takes place Paralogous genes: result fromgene duplicationo More than one copy inthe genomeo Can diverge within the clade that carries themParalogous Genes: The Globin gene family has resulted from several gene duplication events Choose the pair of paralogous genes from the following list.1. A human alpha hemoglobin and chimpanzee alpha hemoglobin – orthologous, homologous2. Two alleles of the human alpha hemoglobin gene – different variety of same gene3. Mouse insulin gene and yeast mating type gene – not connected in any way4. Two different olfactory receptor genes – paralogous Chapter 27: ProkaryotesOne thing that E. coli and other bacteria have in common with eukaryotes is the presence of _____. 1. Chloroplasts 2. Mitochondria3. Nucleus4. Ribosomes Concept 27.1: Structural and functional adaptations contribute to prokaryotic success Prokaryotes are unicellularo Some colonial forms Range in size from 1-5 micrometerso Thiomargarita namibiensis (750 micrometers) No membrane-bound organelles Circular chromosomesProkaryotic cells have a variety of shapes The three most common are spheres (cocci), rods (bacilli), and spirals (spirilli) Cell-Surface Structures Cell Wall:o Maintains cell shape, provides physical protection, prevents cell from bursting in a hypotonic environmento Composed of peptidoglycan in bacteriao May also have an outer phospholipid membrane Cell Surface Structures: A capsule (a sticky layer of polysaccharide or protein) may cover the cell wall of many prokaryotes Fimbriae and pilli allow prokaryotes to stick to their substrate or other individuals in a colonyMotility: Motile bacteria move by means of flagellaeo Structurally different from eukaroticflagella In a heterogenous environment bacteriaexhibit taxis (ability to move toward or awayfrom certain stimuli)o Positive chemotaxis – moving towarda chemical stimulus
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